Integrated torque motor and throttle body

ABSTRACT

An electrically operated throttle valve assembly  110, 210  having a throttle shaft  18, 218  with a portion extending exteriorly of the throttle body  12.  Rotor  166, 266  is mounted on the extending portion of shaft  18, 218.  A housing  80  concentrically surrounds the rotor  166, 266  and includes a rear wall  86, 286  to which stator  134, 234  is attached. The stator  134, 234  having a plurality of circumferentially spaced pole segments each with a coil is mounted to the rear wall  86, 286  and is concentrically disposed within the rotor  166, 266.  The hollow cylindrical rotor  166, 266  with plural magnets  72, 74, 272, 274  disposed about the inner periphery has a radial web flange  168, 268  which is drivingly attached to one end of the extending portion of shaft  18, 218  with the rotor  166, 266  nested over the stator pole segments. Reducing the size or even eliminating the mounting shaft or bolt  92,  and preferably replacing it with a welded, wound and overmolded stack of laminations provides more winding area for electrically conductive coils to provide more magnetic flux.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is a continuation-in-part application ofparent application Ser. No. 09/193,676, filed on Nov. 17, 1998.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable

MICROFICHE APPENDIX

[0003] Not Applicable

BACKGROUND OF THE INVENTION

[0004] 1. Field of the Invention

[0005] The present invention relates generally to air inlet or throttlevalves, and particularly to throttle valves of the butterfly typeutilized for controlling air inlet flow to an internal combustionengine.

[0006] 2. Description of the Related Art

[0007] In recent times, with the advent of onboard microprocessorcontrollers for vehicle engines, it has been desired to provideelectrically operated control of the vehicle engine throttle in order tomore fully utilize the sophistication of the programs contained withinthe microprocessor for engine fuel delivery and ignition timing controlin order to minimize fuel consumption and reduce exhaust emissions. Ithas also been desired to integrate the throttle control with the onboardengine microcomputer as an adjunct or override for vehicle operatorthrottle pedal movement. It has further been desired to provide anelectrically operated throttle in order to implement the cruise controlfunction and traction control function with the algorithms programmedinto the engine control computer.

[0008] Heretofore, it has been proposed to provide an electric motormounted on the vehicle throttle body to provide throttle valve rotationin response to an electric control signal provided by the vehicle enginecomputer. However, it has proven difficult to mount an electric motor ona vehicle throttle body and provide proper calibration of the motor forprecise positioning and rotation of the throttle after mounting of themotor on the throttle body.

[0009] Heretofore, it has been proposed to provide stepper motors andrelatively high rotations per minute (rpm) low torque servomotorsconnected through a speed reducing gear train to provide electricalactuation of the vehicle throttle. However, stepper motors can beprohibitively costly for high volume automotive applications; and,servomotors driving the throttle through a gear train can be difficultto calibrate and can lag in providing the necessary response timerequired for vehicle throttle operation. It has also been proposed touse a torque motor for direct throttle rotation. However, torque motorscan be prohibitively heavy and bulky in order to provide adequate torquefor desired throttle response. Torque motors can also be difficult toassemble on the throttle body and calibrate for proper throttlepositioning. Furthermore, torque motors can require installation andprecise calibration (i.e., rotary orientation) of the motor stator androtor poles with respect to the throttle plate before assembly of thethrottle body to the engine intake manifold. However, when it is desiredto fabricate the throttle body and engine intake manifold as a singleone-piece member, all motor actuators can be quite difficult to assembleand calibrate on such an arrangement.

[0010] U.S. patent application Ser. No. 09/098,974 titled ElectricallyOperated Throttle Valve Assembly, assigned to the Assignee of thepresent invention and hereby incorporated by reference, describes athrottle valve assembly design where the rotor is supported by thethrottle valve shaft. In this design, the shaft 18 extends outwardbeyond its support bearing by the length of the motor as best seen inFIG. 1.

[0011] There still exists a need for an improved design that can reducethe bending moment produced by shaft 18 and mount stator 34 withoutfasteners positioned in the magnetically critical pole outer diameter(O.D.) area therein.

[0012] Still, it is desirable to provide a relatively low cost,lightweight, motorized throttle for a motor vehicle engine which issimple to fabricate, fast in response, lightweight, and requires littleor no calibration upon installation.

BRIEF SUMMARY OF THE INVENTION

[0013] Accordingly, one object of the present invention is directed toreducing the bending moment of the throttle shaft, i.e., reducingdisplacements during vibrations.

[0014] Another object of the present invention is to shorten thethrottle shaft to increase the stiffness of the rotor assembly. Thisallows for a slightly smaller magnetic air gap and results in improvedmagnetic efficiency. Shortening the shaft reduces the inertia due to theshaft which results in improved response time.

[0015] A further object of the present invention is to reduce or eveneliminate attachment bolts from the magnetically critical pole area ofthe stator assembly.

[0016] Still a further object of the present invention is to provide atorque motor assembly design that allows for more winding area in thelaminates for a given motor size by providing an increase in the slotarea available for winding magnet wire around each pole of the stator.This can result in a smaller motor for the same torque.

[0017] Still a further object of the present invention is to provide atorque motor assembly design that allows for more magnetic flux for agiven motor size.

[0018] The present invention provides an improved torque motor assemblydesign constructed preferably integrally with a throttle body and valvewith the motor having a rotor attached to an extending portion of thethrottle shaft. Preferably a portion of the throttle shaft extendsexteriorly of the throttle body with the motor rotor configured as ahollow cylinder and mounted on the shaft and nested concentrically overthe stator. The preferred embodiment of the present invention eliminatesthe mounting bolt(s) for the attachment of metal laminations to thestator assembly, and replaces that design with a welded, wound, andovermolded stack of laminations. The present invention provides a designwith an increase in the slot area available for winding magnet orelectrically conductive wire around each pole of the stator. In analternate embodiment of the present invention, a second shaft isprovided substantially centrally through the stator in a lessmagnetically critical area, i.e., the inner diameter (ID). The secondshaft is preferably a through-bolt smaller in diameter than the throttleshaft. The second shaft is rigidly attached to a housing thatconcentrically surrounds the stator and rotor.

[0019] The various features of novelty which characterize the presentinvention are pointed out with particularity in the claims annexed toand forming a part of this disclosure. For a better understanding of theinvention, its operating advantages and specific objects attained by itsuses, reference is made to the accompanying drawings and descriptivematter in which a preferred embodiment of this invention is illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a section view taken transversely through the air inletpassage of one embodiment of a vehicle throttle body;

[0021]FIG. 2 is a section view taken along section indicating lines 2-2of FIG. 1;

[0022]FIG. 3 is a section view taken along section indicating lines 3-3of FIG. 1;

[0023]FIG. 4 is a section view similar to FIG. 1 in accordance with oneembodiment of the present invention;

[0024]FIG. 5 is a section view similar to FIG. 1 in accordance with apreferred embodiment of the present invention;

[0025]FIG. 6 is section view of a 4-pole stator design without a shafttherethrough; and

[0026]FIG. 7 is a section view of a 4-pole stator design with a shafttherethrough.

DETAILED DESCRIPTION OF THE INVENTION

[0027] Referring first to FIGS. 1 and 3, a throttle valve assembly isindicated generally at 10 and includes a throttle body structure 12having formed therethrough an air inlet passage 14 which has disposedtherein a rotatable valve member or butterfly plate 16. The valve member16 is received through a slot 20 formed in a shaft 18 which has one endjournalled in a bearing 22 disposed in a recess 24 formed in a boss 26provided on the body 12. The throttle plate 16 is secured in the slot 20by a pair of screws 32 received through the shaft 18. Shaft 18 extendsthrough the side of passage 14 opposite boss 26 and is journalled in asecond bearing 28 provided in a recess 30 formed in the throttle bodyexteriorly of air inlet passage 14. In the presently preferred practiceof the invention, shaft 18 and its external segment 118 are formed as aone-piece unitary member.

[0028] Shaft 18 extends externally beyond bearing 28 in an externalsegment 118.

[0029] A stator indicated generally at 34 has a pair of oppositelydisposed semi-cylindrical pole segments or shoes 36, 38 which aredisposed in diametrically opposite spaced substantially parallelarrangement. Each of the segments 36, 38 is supported by a longitudinalweb denoted respectively 40, 42 attached to a central hub 44 which has aclearance passage or bore 46 formed therethrough and through which isreceived shaft extension 118.

[0030] Each of the webs 40, 42 has a coil wound thereabout denotedrespectively 48, 50 and which is formed preferably of magnet wire. Thestator 34 is secured to the throttle body preferably by through-boltingwith screws or bolts 52, 54, 56, 58 disposed peripherally about thestator and threadedly engaging the throttle body 12. Alternativelystator 34 may be secured by other techniques, such as, for example,providing lugs thereon which are engaged by clips or mounting brackets.Thus, the stator 34 extends in cantilever from throttle body 12 over theshaft external segment 118.

[0031] An electrical receptacle 60 is provided on the throttle body 12and has electrical terminals provided therein, one of which isillustrated and denoted by reference numeral 62 and which is connectedto one of the leads 64 of coil 48 and is typical of the coilconnections.

[0032] Still referring to FIGS. 1 and 2, a rotor indicated generally at66 has a generally hollow cylindrical configuration and is formed of amaterial with high magnetic permeability. Rotor 66 is disposed over thestator 34 and is supported by an annular web flange 68 having a hub 70secured onto the end of shaft extension 118 preferably by press fitengagement. However, it will be understood that the hub 70 mayalternatively be positively engaged with shaft extension 118 by anysuitable expedient such as a spline fitting, shaft key or weldment.

[0033] Rotor 66 has a plurality of permanent magnets 72, 74 each havinga preferably semi-cylindrical configuration disposed about the innerperiphery of the rotor in circumferentially spaced arrangement to definetherebetween a pair of diametrically opposite disposed air gaps. Ifdesired, rotor 66 may be formed integrally as for example by deepdrawing or extrusion. In the present practice, the rotor is formed of astraight tubular section 76 attached to a flange member 68 by suitablemeans such as fasteners, weldment, metal deformation, or the like.

[0034] Referring now to FIG. 4, where like numerals indicate like orsimilar features, there is shown a sectional view of an improvedthrottle valve assembly generally designated 110 according to thepresent invention. Throttle valve assembly 110 includes a throttle body12 with an air inlet passage 14 and a rotatable valve member 16 disposedtherein. Valve member 16 is received through a slot 20 (as seen in FIG.3) formed in shaft 18 and is secured thereto with suitable fasteners 32.Shaft 18 has one end journalled in a bearing 22 disposed in recess 24formed in the boss 26. In the present invention, shaft 18 only extendsthrough the side of passage 14 opposite boss 26 a sufficient distance toallow for mounting the rotor 166 thereon.

[0035] Preferably, a generally cylindrical housing 80 is connected tothe throttle body 12 at the recess 30. Housing 80 may be attached tothrottle body 12, or more preferably is integrally formed therewith.Housing 80 concentrically receives the rotor 166 therein and provides agap 82 that allows the rotor 166 to rotate therein.

[0036] Rotor 166 has a generally hollow cylindrical configuration and ismade from a material with high magnetic permeability. In thisembodiment, rotor 166 is constructed with a tubular section 84 which isattached by suitable means at one end to the web flange 168. Flange 168includes a centrally located hub 170 with a bore that receives theextending portion of shaft 18 for mounting rotor 166 thereon by way of apress fit engagement, spline fitting, shaft key, weldment or the likefor positive engagement. Rotor 166 further includes a plurality ofpermanent magnets 172, 174 for a 2-pole, or with four magnets for a4-pole configuration. Each magnet 172, 174 preferably has asemi-cylindrical configuration disposed about the inner periphery of thetubular section 86 of rotor 166 in a circumferentially spacedarrangement to define therebetween a pair of diametrically oppositelydisposed air gaps. Rotor 166 alternatively may be formed integrally as,for example, by deep drawing or possibly extrusion.

[0037] A rear wall or cover 86 is attached to the open end of housing 80with any suitable means like fasteners 88, for example. Rear wall 86 hasa centrally located hub 90 with preferably a threaded bore 94constructed to receive a threaded end of a second shaft 92, e.g.preferably a bolt.

[0038] The second shaft 92 extends through stator 134 in substantialaxial alignment with shaft 18 and securely holds the stator in aconcentric orientation within rotor 166. Advantageously, the presentinvention allows for the placement of second shaft 92 in a lessmagnetically critical area of the stator, i.e., substantially centrallypositioned within stator 134. Rear wall 86 in the preferred embodimentincludes at least two recesses 96 for a 2-pole configuration and maycontain four recesses for a 4-pole configuration, each recess 96accommodating one of the pole segments 136, 138 of stator 134. Anopening 98 with a boss portion in the rear wall 86 receives one of theleads 100 from the coil which is typical of coil connections. Lead 100is electrically connected to an electric terminal 162 positioned in anelectrical receptacle 160 situated in opening 98. Ordinarily, the motorwould require two terminals 162, but only one is shown. An O-ring 102 isemployed to provide a seal around opening 98. Stator 134 can still beconstructed of like materials and in a like manner to that of stator 34.In contrast to other designs, second shaft 92 eliminates the need forsupporting rotor 66 in FIG. 1 with the longer shaft 18, 118. The shortershaft 18 in FIG. 4 increases the stiffness of the rotor assembly andreduces displacements during vibrations. This allows for a slightlysmaller magnetic air gap due to smaller safety margins and the resultingimproved magnetic efficiency. By employing second shaft 92 to allow fora shorter shaft 18, the throttle valve assembly 110 produces a smallermoment of inertia resulting in improved response time.

[0039] By providing a shorter shaft 18 in throttle valve assembly 110,the clearance normally provided in the laminates of stator 34 are notrequired in stator 134. Thus, the four laminate attachment bolts 52, 54,56, 58 used in the design shown in FIG. 1 are eliminated. Thoseattachment bolts 52, 54, 56, 58 are situated in a magnetically criticalarea of the stator 34. By replacing these bolts with a single bolt 92 orsimilar mounting means including, without limitation, a pressed pinconnection, rivet through rear wall, welding, or the like in a lessmagnetically critical area, the design of the throttle valve assembly110 of the present invention allows for more winding area in thelaminates. This feature allows a smaller motor to be constructed for thesame torque resulting in weight and cost savings.

[0040] Next, referring now to FIG. 5, where like numerals indicate likeor similar features, there is shown a sectional view of an improvedthrottle valve assembly generally designated 210 according to thepresent invention. Throttle valve assembly 210 includes a throttle body12 with an air inlet passage 14 and a rotatable valve member 16 disposedtherein. Valve member 16 is received through a slot in shaft 218 similarto that of slot 20 (as seen in FIG. 3) formed in shaft 18 and may besecured thereto with suitable fasteners. Shaft 218 has one endjournalled in a bearing 22 disposed in recess 24 formed in the boss 26.In the present invention, shaft 218 only extends through the side ofpassage 14 opposite boss 26 a sufficient distance to allow for mountingthe rotor 266 thereon similar to the embodiment shown in FIG. 4. Also,preferably shaft 218 has a portion with a smaller or reduced diameterupon which rotor 266 is disposed.

[0041] Preferably, a generally cylindrical housing 80 is connected tothe throttle body 12. Housing 80 may be attached to throttle body 12, ormore preferably is integrally formed therewith. Housing 80concentrically receives the rotor 266 therein and provides a gap 82 thatallows the rotor 266 to rotate therein.

[0042] Rotor 266 has a generally hollow cylindrical configuration and ismade from a material with high magnetic permeability. In thisembodiment, rotor 266 is constructed with a tubular section 284 whichmay be integral with or attached by suitable means at one end to the webflange 268. Flange 268 includes a centrally located bore that receivesthe reduced diameter portion of shaft 218 for mounting rotor 266 thereonby way of a press fit engagement, spline fitting, shaft key, weldment orthe like, for positive engagement. Rotor 266 further includes aplurality of permanent magnets 272, 274 for a 2-pole or with fourmagnets for a 4-pole configuration. Each magnet 272, 274 preferably hasa semi-cylindrical configuration disposed about the inner periphery ofthe tubular section 284 of rotor 266 in a circumferentially spacedarrangement to define therebetween a pair of diametrically oppositelydisposed air gaps. Rotor 266 alternatively may be formed integrally as,for example, by deep drawing or possibly extrusion.

[0043] The preferred embodiment of the present invention advantageouslyemploys a plurality of laminations, also referred to as laminates ormetal plates, 300 each having discrete pole segments 302, for examplewith a shape as seen in FIG. 6 for a 4-pole design. A 2-pole design isan alternative and would simply have two less poles 302. The pluralityof metal plates 300 are preferably steel and are about 2 mm. thick. Itshould be immediately apparent that other metals and thicknesses arealso suitable. The plurality of laminations or metal plates 300 arestacked and welded together on an outer surface of the pole segment 302,for example, with a weld bead along an apex 304 of the arc 306 on eachof the pole segments 302. This welding location is intended for thepreferred embodiment. Other locations for welding may also be employed.Approximately fifty or more metal plates 300 which are preferably formedfrom a metal stamping process are stacked in a fixture and weldedtogether with a weld bead extending on the outside surface or diameteras previously mentioned. The poles 302 and winding cavities or slot area308 formed thereby are preferably coated with an epoxy coating or anelectrostatic paint as is known in this art. A terminal interfaceconnector 310 (as seen in FIG. 5) is disposed in position so that afterwinding the electrically conductive coils (magnetic wire) on the polesof the stator 234 (formed by the plurality of laminations 300 weldedtogether) the wires of the coils are connected to terminal connectionstherein and terminate at the electrical terminals 262. The terminals262, only one of which is shown in FIG. 5, pass through the electricalreceptacle 260 through the terminal interface connector 310, which ismade from a non-conductive material, and connect to their respectiveisolated terminal connections therein to the leads of the coils. Thepresent invention encapsulates the coils of the stator 234 with aplastic material 312, like glass filled nylon, using a plastic injectionmolding process. Rear wall 286 is preferably formed integrally therewithat the same time during the plastic injection molding process.

[0044] By eliminating the mounting bolt 92 for the attachment of themetal laminations to the stator assembly, and replacing it with awelded, wound, and overmolded stack of laminations, the preferredconstruction and design of the present invention increases the windingcavity area for winding electrically conductive coils around each poleof the stator. This allows for more magnetic flux for a given motorsize. Likewise, if available flux is not the limiting factor in themotor design, but flux carrying capacity of the lamination stack is,then the winding area dimensions can be adjustable to trade winding areafor metal area. This allows for flexibility in the design to positionmore metal where necessary for carrying the flux.

[0045] In operation, excitation of coils in the stator 134, 234 bycurrent flow in one direction will cause rotor 166, 266 to rotate by anamount of about 160 degrees in one direction for a 2-pole design (about80° for a 4-pole design). By reversing polarity, energization of thecoils produces current flow in an opposite direction which causes therotor to rotate an equivalent distance in the opposite direction.

[0046] The throttle valve 110, 210 according to the present inventionallows for several advantages in assembly including, without limit, thefollowing. The design of the instant invention provides a drop-infeature for rotor 166, 266 into housing 80. Then, stator 134, 234 isinserted therein. Rear wall 86, 286 seals the throttle valve assemblyproviding protection from dust, dirt, water, snow, or the like, i.e.,environmental protection in a fairly hostile environment. The assemblyprocess of the throttle valve 110, 210 is also cost effective andprovides similar benefits.

[0047] The present invention requires no electrical connections duringfinal assembly since the stator 134, 234 has all of its connectionscompleted prior to placement within rotor 166, 266.

[0048] The design of the present invention allows for the integration ofadditional functions like position sensing, for example, into the statorsubassembly and use of its electrical connector.

[0049] In view of the foregoing, the throttle valve assembly 110, 210offers the following advantages: low shaft bending, increased windingarea, low rotor inertia, and an improved assembly technique. Theremovable rear wall 86 allows assembly of the stator 134 thereon priorto fastening wall 86 onto housing 80. This facilitates alignment andspacing.

[0050] The throttle assembly 210 employs a welded and overmoldedlamination stack 300 that provides more winding area, approximately fourpercent more area as shown and calculated between FIGS. 6 and 7,compared to a bolted together lamination stack 400. By completelyeliminating the mounting bolt 492 for the attachment of the metallaminations to the stator assembly, and replacing it with a welded,wound and overmolded stack of laminations, an improved design isconstructed that allows for an increase in slot area or winding cavityarea 308 as compared with the winding cavity area 408 for windingelectrically conductive coils around each pole of the stator. Theconstruction of throttle assembly 210 allows for more magnetic flux fora given motor size. If flux is not the limiting factor in the motordesign, but flux carrying capacity is, then the slot area dimensions canbe adjusted to trade winding area for metal area. This design allowsmore metal to be placed where it is needed to carry the flux.

[0051] While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles. Although the inventionhas hereinabove been described with respect to the illustratedembodiments, it will be understood that the invention is capable ofmodification and variation and is limited only by the following claims.

I claim:
 1. An electrically operated throttle valve assembly comprising:(a) a throttle body defining an air passage therethrough; (b) a shaftmember extending transversely through said passage, said shaft having avalve member thereon, said shaft being journalled in a first and secondbearing surface disposed on opposite sides of said passage for rotationtherein, wherein said valve member is rotated with said shaft; and saidshaft having a portion extending externally of said throttle body; (c) ahollow generally cylindrical rotor formed of material having arelatively high magnetic permeability, said rotor being disposed only atone end on said extending portion of said shaft for rotation therewith;(d) a plurality of magnets disposed in the hollow of said rotor incircumferentially spaced arrangement; (e) a stator formed of a pluralityof metal plates attached together on an outer surface thereof, saidstator having a plurality of discrete pole segments disposed thereabout,each segment having an electrically conductive coil wound thereon, saidstator being encapsulated with a plastic material, and being located ina concentric orientation within said rotor, said stator being fixedlyattached to a rear wall of a housing surrounding said stator and saidrotor; and, (f) terminal means connected to each of said electricallyconductive coils, said terminal means adapted for external electricalconnection thereto.
 2. The throttle valve assembly defined in claim 1wherein said valve member comprises a butterfly plate.
 3. The throttlevalve assembly defined in claim 1 wherein said plurality of metal platesforming said stator are welded together.
 4. The throttle valve assemblydefined in claim 3 wherein said plastic material encapsulating saidstator forms said rear wall of said housing.
 5. The throttle valveassembly defined in claim 4 wherein said plastic material comprises aglass filled nylon material.
 6. The throttle valve assembly defined inclaim 1 wherein said rotor is formed of a generally straight cylindricalshell attached to a radially extending flange having a bore forreceiving said extending portion of said shaft therein, said extendingportion of said shaft being received within the bore of said flangehaving a reduced diameter.
 7. A method of making a torque motorassembly, comprising the steps of: (a) stacking a plurality offerromagnetic laminates, each laminate having discrete pole segments;(b) welding the laminates together for forming a stator; (c) disposingelectrically conductive coils on the pole segments of the stator; (d)encapsulating the stator and coils with a plastic material; (e)supporting the encapsulated stator on a base structure; (f) disposing aplurality of magnets on an annular rotor and disposing said rotor andmagnets over said stator; and (g) journaling said rotor for rotationabout said stator.
 8. The method defined in claim 7, wherein said stepof welding the laminates together comprises the step of providing a weldbead along an outer surface thereof.
 9. The method defined in claim 7,wherein said step of journaling comprises the step of journaling saidrotor on a member selected from the group consisting of said stator andsaid base structure.
 10. The method defined in claim 9, wherein saidstep of encapsulating the stator includes the step of injection moldingan encapsulation layer on the stator and forming a rear wall for thebase structure therewith.
 11. A torque motor assembly made in accordancewith the method of claim 7, comprising: (a) a stack of ferromagneticlaminates having discrete pole segments welded together to form astator; (b) an electrically conductive coil disposed on each of the polesegments of said stator; (c) an encapsulating layer on the stator andcoils; (d) a generally cylindrical rotor having a plurality of magnetsdisposed therein in a circumferentially spaced arrangement; and (e) abase structure, said base structure constructed to support saidencapsulated stator and coils, said rotor being journaled on said basestructure and adapted to rotate about said stator.
 12. An electricallyoperated throttle valve assembly comprising: (a) a throttle bodydefining an air passage therethrough; (b) a first shaft member extendingtransversely through said passage, said first shaft having a valvemember thereon, said first shaft being journalled in a first and secondbearing surface disposed on opposite sides of said passage for rotationtherein, wherein said valve member is rotated with said first shaft; andsaid first shaft having a portion extending externally of said throttlebody; (c) a hollow generally cylindrical rotor formed of material havinga relatively high magnetic permeability, said rotor being disposed onlyat one end on said extending portion of said first shaft for rotationtherewith; (d) a plurality of magnets disposed in the hollow of saidrotor in circumferentially spaced arrangement; (e) a stator formed ofmaterial of relatively high magnetic permeability, said stator beingdisposed in a concentric orientation within said rotor, said statorhaving a plurality of discrete pole segments disposed thereabout, eachsegment having an electrically conductive coil wound thereon; (f) asecond shaft member extending through said stator and being situated insubstantial axial alignment with said first shaft member, said secondshaft member being located substantially centrally in said stator in aless magnetically critical area of said stator, said stator beingprovided with more winding area for the electrically conductive coilwound thereon, said second shaft member holding said stator in theconcentric orientation within said rotor with one end of said secondshaft member being fixedly attached to a rear wall of a housingsurrounding said stator and said rotor; and, (g) terminal meansconnected to each of said electrically conductive coils, said terminalmeans adapted for external electrical connection thereto.
 13. Thethrottle valve assembly defined in claim 12 wherein said second shaftmember is smaller in diameter than said first shaft member.
 14. Thethrottle valve assembly defined in claim 13 wherein said through-boltbolt is smaller in diameter than said first shaft member.